The invention relates to a ring and traveller system for spinning and twisting frames.
In ring spinning, travellers that rotate on rings at high relative speed are used. Under industrial conditions, the travellers currently attain a relative speed of up to 40 m/s without active lubrication.
The manufacture of the ring and the traveller from hardened steel or steel wire is known in the art (DE-A1-32 10 133).
Worldwide, there are about 150 million ring spindles, all of which are equipped with metal rings. In the ring spinning works of highly industrialized countries, machine-related performances of more than 90% are currently being achieved. However, the annual performance is considerably lower due to necessary maintenance and repair work. A substantial portion of the down time of a ring spinning frame is attributable to replacing the traveller which must be replaced at regularly recurring intervals. Depending on the spinning conditions, the abrasion stresses acting on the traveller are so high that the traveller must be changed frequently, i.e. daily, weekly, or at most every second week. As the traveller becomes increasingly worn, the yarns collect more burls and fibre accumulations and become more hairy. This last condition in particular causes problems in subsequent processing.
The changing of the traveller and the subsequent re-starting of the ring spinning frame are manual operations. Since all of the about 600 to 1,100 spinning points of the ring spinning frame have to be replaced with new travellers, such operations require a considerable number of personnel. Inevitably, all the filaments are broken. Occasionally, the used travellers fall into the machine cavity. The fallen travellers are difficult to remove.
The ring, as a complementary part, has a load-dependent service life ranging from one to four years. A decline in the efficiency of the rings is inevitably accompanied by an increase in the thread breakage rates, increased traveller wear and deteriorating yarn properties. Replacement of these rings necessitates extensive machine down time because of the ring change-over and the complicated, but necessary, centering of the new rings. Subsequently, ring breaking-in periods lasting several days are required resulting in additional production losses due to frequent traveller change and lower spindle speed.
If this ring breaking-in period is not performed according to the manufacturer's specifications, the rings may suffer damage. With the high quality standards demanded of ring-spun yarn, this running-in phase results in the production of wasted yarn.
Extensive development work has revealed that the central problem lies in the abrasion of material in the form of hard micro-welds of the traveller material onto the ring surface. As a result, an originally ideally polished ring surface is worn into a microscopic mountain range. The traveller, which slides over such a surface, exhibits an increasing tendency to scuff. The traveller's running conditions on the ring become continuously worse and the efficiency of the machine deteriorates. In addition, the pairing of a steel ring and steel traveller as a galvanic element has the propensity to corrode during machine stoppages (work holidays and so on) or in a hostile environment. Re-starting of the machine is then associated with serious breakdowns in the form of high thread breakage rates. The end result is considerable economic loss attributable to machine down time.
Attempts at active lubrication of the ring and traveller system in cotton spinning have lead to no improvement. Since only extremely small amounts of lubricant can be used, the exact dosing, where thousands of spindles are involved, is an extremely difficult task. Over-dosing results in the cops becoming soiled.
Many years of research work in the fields of improving the surface quality, degrees of hardness, metal alloys, coatings, both of the traveller and of the ring, have so far failed to satisfactorily solve these problems.
Because the traveller is considerably less expensive than the ring, the hardness of the traveller has always been specified to be somewhat less than the hardness of the ring, so that the traveller wears before the ring.
For a long time there has been an attempt to provide the ring with a ceramic coating (DE-A1 38 39 920). The very hard ceramic ring causes an over-proportional wear of the traveller. The traveller cannot survive even one drawing-off operation, that is to say, a spinning time of 4 to 8 hours.
Providing the traveller with a ceramic coating layer has also been attempted (DE-A1 35 45 484). The ring and traveller system did not, however, satisfy the required demands of a protracted service life.
The invention is therefore based on the problem of developing a ring and traveller system for spinning and twisting frames which has a significantly improved service life and allows a higher production speed, with identical or improved yarn properties, and thus makes a material contribution to increased economic efficiency.
The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this specification. For a better understanding of the invention, its operating advantages and specific objects obtained by its use, reference should be made to the accompanying drawings and descriptive matter in which there is illustrated and described a preferred embodiment of the invention.